Ulfiana, Desyta (2018) Studi Efektivitas Pola Pemasangan Baffled Block pada Peredam Energi dalam Mereduksi Energi Aliran. Masters thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Peredam energi berfungsi untuk menstabilkan aliran air sehingga tidak terjadi gerusan yang membahayakan geometri sungai hilir yaitu pada bagian dasar dan tebing sungai. Fenomena perubahan kondisi pengaliran dari super kritis menjadi sub kritis yang menyebabkan terjadinya loncatan hidraulik (hydraulic jump) digunakan oleh peredam energi untuk mereduksi energi aliran. Tipe peredam energi yang paling sering digunakan adalah kolam olak yang dilengkapi dengan baffled block. Baffled block berfungsi untuk menimbulkan locatan hidraulik dan mereduksi kecepatan aliran.
Keefektifan fungsi kolam olak dengan baffled block ini dalam menstabilkan air masih kurang. Hal ini dibuktikan dengan masih banyak terjadi peristiwa gerusan pada tebing dan dasar sungai hilir bendung atau bendungan. Berdasarkan fungsi baffled block yang signifikan tersebut, maka dilakukan penelitian tentang pola pemasangan baffled block di kolam olak.
Pada penelitian ini, dimodelkan 4 variasi pola pemasangan baffled block dengan lima variasi debit. Variasi dilakukan dengan mengubah jarak longitudinal dan lateral baffled block. Penelitian dilakukan dengan melakukan analisa parameter hidraulik aliran, yaitu kecepatan aliran, bilangan Froude dan kehilangan energi relatif aliran pada hilir peredam energi. Berdasarkan hasil analisa, model 1 memiliki kecepatan rata-rata aliran 1,85% lebih kecil dari model seri 0 atau model asli USBR tipe III. Sedangkan model 2 dan 3 masing-masing memiliki kecepatan rata-rata aliran 1,20% dan 3,01% lebih besar dari model 0. Berdasarkan analisa juga didapatkan, model 1 memiliki bilangan Froude dengan nilai 0,52% lebih kecil dari model seri 0. Sedangkan model 2 dan 3 masing-masing memiliki bilangan Froude dengan nilai 0,34% dan 1,36% lebih besar dari model 0. Berdasarkan hasil analisa kehilangan energi relatif aliran didapatkan model seri 1 memiliki nilai kehilangan energi relatif dengan nilai 0,52% lebih besar dari model seri 0. Sedangkan model 2 dan 3 masing-masing memiliki nilai kehilangan energi relatif dengan nilai 0,41% dan 0,99% lebih kecil dari model 0. Berdasarkan hasil pengamatan juga didapatkan empat model seri kolam olak pada penelitian ini tidak bekerja secara efektif dalam meredam energi aliran pada TW depth kurang dari 0,8 D2. Berdasarkan hasil tersebut, maka pola pemasangan baffled block dengan jarak antar baffled block disesuaikan sehingga letaknya berada diantara chute block (model 1) memiliki kemampuan menstabilkan aliran lebih baik dibandingkan model kolam olak USBR tipe III.
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Energy dissipator serves to stabilize the flow of water so that no scouring happens. Scouring can endanger the geometry of downstream river that is at the riverbed and river bank. The changing of stream conditions from supercritical conditions to subcritical conditions causes a hydraulic jump that is used by energy dissipator to reduce the flow energy. Type of energy dissipator which is frequently used is stilling basin that equipped with baffled blocks. Baffled blocks serve to generate hydraulic jump and reduce the flow velocity.
The effectiveness of this stilling basin in stabilizing the flow water is lacking. This is proved by many incident which scouring still occur on downstream riverbed and riverbank of the weir, even it has this stilling basin. Based on the problem above, then the research about the installation of baffled block pattern has been done.
In this research, four variations of baffled block installation pattern has been modeled with five variations of discharge. Variation has done by changing the longitudinal and lateral distance of baffled block. The study was conducted by analyzing the hydraulic flow parameters, that is flow velocity, Froude number and relative energy loss on the downstream of energy dissipator. Based on the analysis results, model 1 has an average flow velocity of 1,85% smaller than the model series 0 or the original model of USBR type III. While model 2 and 3 have average flow velocity of 1,20% and 3,01% greater than model 0. Based on the analysis also obtained, model 1 has Froude number with value 0,52% is smaller than the model series 0. While, models 2 and 3 each have Froude number with values of 0.34% and 1,36% greater than model 0. Based on the results of the relative energy loss analysis, model 1 has a relative loss energy value of 0,52% larger than model series 0. Models 2 and 3 each have relative loss energy values of 0,41% and 0,99% smaller than model 0. Based on the observations also obtained that all four stilling basin model in this research does not work effectively in reducing the flow energy at TW depth less than 0.8 D2. Based on these results, the pattern of baffled block installation with the distance between baffled blocks was adjusted so that is located between chute block (model 1) has the ability to stabilize the flow more effective than the model USBR type III.
| Item Type: | Thesis (Masters) |
|---|---|
| Additional Information: | RTS 627.13 Ulf s-1 3100018074360 |
| Uncontrolled Keywords: | Baffled block; energy dissipator; installation pattern; hydraulic jump |
| Subjects: | T Technology > TC Hydraulic engineering. Ocean engineering > TC1680 Offshore structures T Technology > TC Hydraulic engineering. Ocean engineering > TC555 Spillways. Energy dissipation. Hydraulic jump. T Technology > TC Hydraulic engineering. Ocean engineering > TC812 Irrigation |
| Divisions: | Faculty of Civil, Environmental, and Geo Engineering > Civil Engineering > 22101-(S2) Master Theses |
| Depositing User: | ULFIANA DESYTA |
| Date Deposited: | 15 Feb 2018 05:30 |
| Last Modified: | 11 Jun 2020 07:53 |
| URI: | http://repository.its.ac.id/id/eprint/49565 |
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